The music industry is starting a second round of tests to select a technology to identify digital musical signals as part of its efforts to crack down on rising Internet piracy.

The decision to start new tests, after none of the technologies submitted in last year's first round were deemed suitable, will delay the adoption of an industry-wide digital identification system by up to six months.

The delay highlights the difficulties faced by the music industry as it tries to prepare for an era in which music will increasingly be delivered directly to consumers on the Internet or other digital networks.

Unofficial estimates suggest there are already 1,800 pirate Internet jukeboxes from which consumers can download illicit digital copies of albums and singles. The adoption of an industry-wide system to identify digital musical signals is regarded as one of the most important technical safeguards. Such a system would use embedded signalling technology to enable companies to monitor any broadcasts of their music, and whether any royalties are owed to them.